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Re: SPI Maximum speed

Posted: Thu Oct 11, 2018 2:43 am
by ESP_Sprite
Note the crystal doesn't really matter; the ESP32 normally uses a PLL to derive the CPU frequency from this, then divides the CPU frequency by an applicable number to get the 80MHz APB clk.

Re: SPI Maximum speed

Posted: Thu Oct 11, 2018 10:41 am
by Vader_Mester
anakyr wrote:I'm 100% sure that I have a 40MHz crystal. Check attachment too. I will try first to include SPI_DEVICE_NO_DUMMY in order to ignore this checking, as the error message in red is saying. If it doesn't work, I will go to the registers :)


Why did I forget about the GPIO MUX?

You can route your SPI directly to pins without using the GPIO MUX matrix, so with it you can achieve higher speeds. I think all your answers are in fact in the red warning message.

Re: SPI Maximum speed

Posted: Thu Oct 11, 2018 12:15 pm
by anakyr
Thanks a lot for the answers. Using this dummy flag I was able to produce 40 MHz at the MOSI.